In grinding mills such as ball mills, the operation is monitored and/or controlled in the prior art by instrumentation primarily solely by sensing the sound of the mill, as exemplified in U.S. patents, as follows:
V. Sahmel--U.S. Pat. No. 2,405,059--July 30, 1946 PA1 D. Weston--U.S. Pat. No. 2,766,941--Oct. 16, 1956 PA1 H. Stockmann et al.--U.S. Pat. No. 3,944,146--Mar. 16, 1976.
In these patents, a single signal is monitored for processing. However, in R. Bradburn et al.--U.S. Pat. No. 4,026,479--May 31, 1977, a computer processes signals from several sources to optimize performance in a complex system of ore grinders with a water feed system.
Some of the conditions measured to effect controls are sound in two concurrently operating mills, level of materials being pumped, and cyclone overflow particle size and density. Both water and ore feed are controlled by the computed result from the monitored conditions, such as a comparison of the feed with the rod-mill sound in a matrix memory to determine when an overload or underload condition exists.
While the foregoing equipment can in an elementary way sense certain mill conditions and control flow of materials to improve performance, there is no ability of the equipment to show relatively unskilled operators the mill conditions to create an understanding of the reactions of different raw materials, additives, etc. passing through the mill. Nor has there been provided any historical record of the mill operation for analysis of past mill conditions.
Furthermore, all the prior art instrumentation is devoid of a realistic relationship to the mill internal operational efficiency which seriously affects operating conditions particularly when variable conditions exist affecting flow, grinding or output product characteristics such as with the use of additive chemicals.
In addition, it is not known in the prior art how to provide universally useful instrumentation that may be employed at a variety of different mills without special tailoring or custom installation and fitting to meet the different mill conditions.
Also the use of sound signals is restrictive not only to particular mill conditions which change with material content being ground, etc., but it also is subject to environmental noise, mill location, etc., all of which can lead to problems of interpretation of signal meaning. A much more reliable signal source is desirable for adequate monitoring or control of mill conditions.
Accordingly, it is an objective of this invention to provide improved instrumentation of a type that can not only be adapted simply to a variety of different mill conditions, but which will provide a historical record of mill operation and a video display panel that will enable an unskilled operator to understand the milling process and to run the mill at optimum production levels.
Other objectives, features and advantages of the invention will be found throughout the following description, drawing and claims.